Control system for farm lighting plants



y 2, 1931. T. w. DRURY I CONTROL SYSTEM FOR FARM LIGHTING PLANTS Filed Dec. '7. 1928 me UK m mm C 8 M; 2 3

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G I .2 3 3 5 G J 2 7 4 5 62 z z a 4 8 3 7 O a 3 m 2 J 0 it INSULATION INVENTOR Thomas W. Drux'y Patented May 12, 1931 FUN/[TED "STATES PATE/NTOFFICE THOMAS W. DRURY, OF WILKINSEURG, PENNSYLVANIA; ASSIGNOR- TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONTROL SYSTEM FOR FARM LIGHTING PLANTS Application filed December 7, 1928. Serial n..a24,522.

" I This invention relates generally to control systems for electric power plants such struction, automatic and eflicient in its operation and easily manufactured and installed.

Another object of the invention is toprovide for automatically controlling .the choker valve of a carburetor for an internal combustion engine to obtain quick starting and economical running of the engine.

And a further object of the invention is to provide for-controlling the choker valve of an internal combustion engine both in response to the speed of the engine and in accordance with predetermined temperature conditions; y

Other objects of the invention 'will be obvious when the following specification is considered in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic illustration of c1rcuits and apparatus arranged in accordance with the invention;

Fig. 2 is a schematic illustration of an internalcombustion engine showing how control apparatus shown in Fig. 1 may be applied to the carburetor to regulate the fuel supply, and

Fig. 3 is a view, of a speed responsive switch employed in conjunction with the circuits and apparatus shown in Fig. 1.

In the system shown in thedrawings, a battery 1 may be provided for supplying electric current at any suitable voltage to a workcircuit including supply conductors 2 and 3 and electric power consuming devices 4, as, for example, incandescent lamps. To provide for the charging of the battery 1 and the Y supplying of additional current; to the work circuit when certain conditions, to be hereinafter set forth; prevail in the work circuit,

a dynamo electric. machine 5 and an internal combustion engine 6 are provided.

The engine 6 may be mechanically coupled to the shaft 7 of the machine 5 in any suitable or well known manner. As shown, the machine 5 is of the shunt type and comprises an armature 8 and a shunt field winding 9.

In order that the machine 5 may be connected across the terminals of the battery 1, or disconnected therefrom, an electromagnetic switch 10 biased to open position is provided.

The engine 6 is provided with a carburetor 11 having an air inlet conduit 12 and a conduit or manifold 13 for conveying the fuel mixture to the explosion chamber of the engine.

With a view to providing a rich fuel mix- & ture to facilitate starting of the engine 6 when it is cranked, a choker valve 14 is disposed in the air inlet conduit 12. and an electr-o-responsive or solenoid device 15 is provided for actuating the Valve in a manner that will be set forth hereinafter. The carburetor is provided with a throttle 16 and a throttleactuating device 17 of the solenoid type, the operation of which device is responsive to the value of current flowing in the work circuit, which in this case is the supply conductor 2. The engine 6 is provided with an ignition circuit which includes a primary coil 19, a secondary coil 20, a spark plug 21 connected to the coil 20, a timer or circuit interrupter 22 and a condenser 23 connected across the terminals of the interrupter or timer.

Since the machine 5 is of the shunt type,

. the armature will turn in the same direction whether it is operating as a motor or a generator. If the switch 10 is closed to connect the engine 6. Assuming that the explosive mixture developed by the carburetor 11 is of the proper kind, the engine 6 will, when cranked,

start and operate the machine 5 as a generator.

In systems of-the type shown in the drawing, it is desirable to provide for the closing of the switch 10 to initiate the cranking of the engine 6 by the dynamo 5, when the current flowing in the work circuit exceeds a predetermined value, for example, six amperes.

This may be accomplished by the provision of a series relay 24 ,the actuating coil of which is connected in to carry the current that may flow in the work circuit. Therefore, the

5 the engine 6 fails to start after it has been cranked for a predetermined length of time, a cranking time-delay thermal relay 25 is provided for interrupting the energizing circuit of the actuating coil of the switch 10 and the ignition circuit. It is to be noted that thev primary coil 19, the timing device 22 and the condenser 23 are connected in parallel-circuit relation to the operating. coil of the switch It). If the relay 25 has operated to interrupt the energizing circuit of both the operating coil of the switch 10 and the ignition circuit, it will remainin its operated position until the switch contacts 26 and 27 thereof have been reclosed by the operator or attendant. Further detailed description of the relay and its mode of operation will be given hereinafter.

To prevent operation of the relay after the engine has started and has attained a speed of a predetermined value, a speed re- 5 sponsive switch 28 is provided for interruptmg a heating circuit for thermal elements of the relay 25, which circuit and elements will be described hereinafter. For. the present purpose, the switch 28' may be mounted on the commutator end of the armature shaft 7.

In order to cause the choker valve 14'to operate the moment the. engine 6 is cranked by the dynamo 5, a time-delay thermal relay 29 and an electro-responsive device 30 are provided for jointly governing the energization of the actuating coil 31 of the choker valve actuating device 15.

The electro-responsive device 30 comprises a coil 32 and armature 33 disposed for opera- 49 tion thereby to close switch contact members 34 and 35 of the relay 29 when the line series relay 24 and the switch 10 have been closed. The operation of the device 30 prevents the separation of the contact members as 34 and 35 so long as the coil 32 is energized,

but will permit the contact members to be opened by the thermal elements of the relay 29 when the speed responsive switch 28 has been operated to effect the deenergization T. of the coil 32. Further detailed description of the relay 29 and its mode of operation will be given hereinafter.

The series relay 24 comprises an actuating coil 37 an armature 38, and a contact bridg- 1 ,ing member 39 disposed for operation by the armature. The armature 38 may be biased towards a position in which the contact members of the relay 24 are open, by means of a spring 41 positioned between a fixed support 42 and an adjustable or calibrating suport 43. The biasing force may be regulated y the calibrating support 43 that makes threaded engagement with an extension 44 of the armature 38. The position of the movable support 43 will determine the value of current flowing through the coil 37 of the relay 24 at which the contact members of the relay will be closed. The position of the support 43, hence the degree of compression initially applied to the spring when the relay is in the open position, will determine .a current flow of six amperes through the coil 37 may be required to close the contact members of the relay 24. The relay having been closed, a smaller value of current than six amperes will maintain it closed; therefore,

if the current is reduced to a value below six amperes, a balancing point will be'reached at which the magnetic pull of the coil on the armature will balance the pull of the spring 41 on the armature. If the current is reducedstill further, the spring 41 will overcome the magnetic pull of thecoil and the relay will be actuated to its open-circuit'position. The value of current traversing the coil 37 at which the relay will drop out or open may be as low as three amperes when the closing value of current is six amperes.

The relay 25 comprises a support 46 pivoted at 47 on which the. contact member 27 is mounted, a latch 48 pivoted at'49 and biasedtowards the right by a spring 50 as shown in Fig. 1, and two strips of bimetal 51 and 52, the lower ends of which may be stationarily mounted as at 53 and 54. Movement of the free ends of the bimetal strips 51 and 52 may be diirans'mitted to the latch 48 through a pushro 55.

When the contact members 26 andw27 of the relay 25 are closed, the coil of the switch 10 and the ignition circuit for the engine 6 may be establishedwhen the relay 24 is closed. In order to cause the contacts 26 and 27 to be opened, if the engine fails to start after it has been cranked for a predetermined length of time the bimetal strips 51 and 52 are provided with electric heating elements or resistors 56 and 57.

The resistors 56 and 57 may be connected in parallel-circuit relation across the armature of the machine 5 when the contacts of the relay 24 are closed. When the strips 51 and 52 have been heated to a temperature of a predetermined value, their free ends will deflect towards the left, thereby actuating the latch 48 to a position at which the pivoted support 46 will be released to the position shown in Fig. 1 of the drawings. In this position, the contacts 26 and 27 are opened whereby the coil of the switch 10 and the ignition circuit for the engine 6 are deenergized.

Further cranking of engine 6 is precluded perature move in either direction, i. e. to the right or left, it follows that the engine may be cranked for a longer period of time in cold weather than in hot weather.

The relay 29 is substantially identical inconstruction to the relay 25 and comprises a support '59 pivoted at one end, a latch 60 therefor, strips of bi-metal 61 and 62 provided with heating elements or resistors 63 and 64 connected in parallel-circuit relation to each other and'a push-rod 65 for actuating the latch 60 in response to movement or deflection of the free ends of the bimetal strips 61 and 62. It is to be noted that the device 30 is utilized for actuating the support 59 to close the switch contacts 34 and 35.

When the coil 32 of the electro-responsive device 30 is energized, the armature 33 is moved upwardly thereby actuating the support 59 to a position in which it will be latched by the latch 60. In this position the contacts 34 and 35. are closedu When the contact members of the relays 25 and 29', and the centrifugal switch 28 are closed, circuitsfor the resistor heating elements 56 and 57, 63 and 64 and the actuating coil 31 of the carburetor choker valve actuating device will be established; It is to be noted that the resistor elements 63. and 64, and the coil 31 are connected in parallelcircuit relation-to each other across the armature 8 of the machine 5. A

The-construction of the speed responsive or centrifugal switch 28 as embodied in system herein disclosed, isshown more particularly in Fig. 3"o'f the drawings. This switch comprises a supporting plate 67 provided with an opening to receive the shaft 7 of the generator, a contact supporting member 68 of insulating material secured to the bottom of the supporting plate 67 and a movable con-, tact supporting member 69 disposed for vertical movement with respect to the stationary plate 67. A resilient contact-bridging member 70 is mounted on the movable member 69 and is disposed to engage stationary contact members 71 and 72"carried by the contact supportingmember 68. The contact members are bridged when the member 68 1s in the position shown in Fig. 3 of the drawings. 4

In .order to effect quick make-and-break of the bridging member 70 with respect to the stationary contact members 71. and 72,

leaf springs 73 and 74 are provided. One end of each of these springs engages stationary lugs 75 and 76 mounted on the plate 67 and the other ends thereof engage lugs 77 I and 78 mounted on the movable contact supporting member 69. As will be noted, the

leaf springs 7' 3 and 74 are normally held in compression between the lugs as is evident from the fact that they appear to be bowed or deflected, as shown in Fig. 3. The leaf springs 73 and 74, the movable support 69 and the stationary supports 67 operate as a toggle mechanism to effect quick make-andbreak of the contact bridging member 70 with respect to the stationary contact members 71 and 72. In order to provide for the operation of the switch in accordance with the speed of iv rotation of the armature 8 of the machine 5, a circular plate 80 is keyed'to the shaft 7 in any suitable manner and provided with a plurality of Weights -81 to 83, inclusive.

Each ofthe weights arep'ivotally mounted at one end on the plate 80and biased by springs 84 so as to oppose the centrifugal force imparted thereto when the shaft 7 is turning. As will be observed, the weights 81 to 83, inclusive, are so positioned thatthey will pass between lugs 85 and 86 mounted on the movable contact supporting plate 69.

' If the shaft 7 is turning faster than a certhe free ends of the weights 81 to 83, inclusive, will swing outwardly against the lug 85 to actuate the toggle mechanism andthereby cause separation of the contact bridging.

member 70 from the stationary contacts 71 and 72 with a' snap action. If the number of revolutions per unit of time at which the shaft 7 is turning falls below a predeterbers will 'move towards the position shown in Fig. 3 of the drawings and cause the toggle mechanism to operate to effect reclosing of the bridging member 7 0 upon the stationary contact members 71 and 7 2.

If the current flowing in the work circuit ample, below six amperes, the storage battery 1 will supply thecurr'ent. If the current demand exceeds six amperes, the contact members of the relay 24 will be closed by the coil tain number of revolutionsper unit of time,

is below a predetermined value, as for ex-- These circuits, menteryl through the supply conductor 2, the

contact bridging member 39 of the relay 24,

conductor 87, contact members 26 and 27 of the relay 25, junction point 88, the o crating coil of'switch 10 to the supply con uctor 3 and the battery 1. The circuit forthe coil 19 of theignition apparatus may be traced from 105 mined value, thefree ends of the weight memof the relay 24, conductor 89, the contact members of the centrifugal switch 28, conductor 91, the resistor elements 56 and 57, and conductor 92 to the armature 8 of the dynamo 5.

The circuit for the coil 32 of the electroresponsive device 30 may be traced from the battery '1- through the supply conductor 2, jumper 39', contact bridging member 39 of the relay 24, conductor 89,' the contact members of the centrifugal switch 28, conductor 95, the coil 32 of the electro-responsive device 30, and conductor 92 to the armature 8 of the dynamo 5. The coil 32 having been energized, the pivotally mounted member 59 will be actuated to the position in which it is latched by the latch 60 and the contact members 34 and 35 of the relay 29 closed.

When the contact members 34 and 35 are closed, circuits for the resistor elements 63 and 64 provided for the bimetal strips 61 and 62 respectively, and the coil 31 of the chokerva ve actuating-device 15 .are established.

These circuits may be traced form the battery 1 through supply conductor 2, the contact bridging member 39 of the relay 24, conductor 97, contact members 34 and 35 of the relay 29, conductor 98, then the resistor elements 63 and 64 and the coil 31 connected in parallel, circuit relation and back to the battery 1 throu h conductors 99 and 93 and the swltch 10. en the coil 31 is energized, the choker valve 14 is closed to restrict the flow of air into the carburetor 11.

When the switch 10 has been closed as previously stated herein, the machine 5 will operate as a motor to crank the engine 6. If

starting conditions of the engine 6 are prop er, it will respond to the cranking-and operate like any other internal combustion engine and will drive the dynamo 5 as a generator. When the speed of the generator exceeds a predetermined value, the centrifugal switch 28 will operate to disengage the. bridging member 70 fromthe stationary contact members 71 and 72. Deener'gization-of the resistor elements 56 and 57 of the relay 25 and the coil 32 of the switch contact closing device 30 of the relay 29 is thereby effected. The contacts 26 and 27 of the relay 25 will therefore remain closed to permit continued operation of the engine 6 and the dynamo 5 a as a generator to supply charging current to be observed in this connection that so long as the coil 32 of the device 30 is energized, the contact members-34 and 35 will be closed even though the latch has been actuated to the position in which the pivotally mounted member 59 will fall by the action of gravity to the position shown in Fig. 1 of the drawings. It is to be noted that since the bimetal strips 61 and 62 are responsive to ambient temperatures, the choker valve will be closed longer in cold weather than hot weather which is a condition to be desired.

In order that the output of the motor 6 may be regulated in accordance with the power demand, required thereof, the coil of the throttle-actuating device 17 is connected in series with the supply conductor 2. The greater the current flowing in the supply conductor 2, the greater will be the pull of the coil upon'the amature of the throttleactuating device 17. Therefore, the throttle valve will be opened or'closed in accordance with the power demand on the engine to admit more or less of the fuel mixture into the explosion chamber of the engine.

If the currentin the work circuit falls below six amperes, but not to a value sufficient to cause the relay 24 to open its contact members, the engine 6 will continue to operate to drive the machine 5 as a generator but if the current falls to a certain value at which the spring 41 will overcome the pull of the coil 37 on the amature38, the relay will drop out and effect an opening of the switch 10. When the contact members of the relay 24 are opened, the ignition circuit and the circuit for the actuating coil of the switch 10 will be deenergized. Consequently, the motor is stopped and the dynamo 5 disconnected from the battery.

From the foregoing description, it is apparent that since the battery is utilized merely for supplying small uantities of power to the work circuit, the 'attery may e of light construction and of small capacity because the generator operates to supply the excess load demand of the work circuit and also .to recharge the battery each time the motor 6 and the machine 5 are started as a motor-generator unit. The system includes a minimum of relays and switches, the device will operate satisfactorily with very little attention and is completely automatic in its operation.

Since changes may be made in the circuits and apparatus of the present embodiment without departing from the spirit and scope driven by the engine, a battery disposed to be connected across the generator to operate it as a motor to crank the engine, a centrifugal switch responsive to the speed of the generator, a coil connected across the generator for actuating the choker valve, a thermostatically operated switch for controlling the energization of the choker valve actuating coil, and an electromagnetically operated latch for controlling the operation of the thermostatically operated switch, said latch being dependent for its operation upon the I centrifugal I switch.

2. In a power system in combination, an internal combustion engine provided with a choker valve, a generator disposed to be driven by the-engine, a batterydisposed to be connected across the generator to operate it as a motor to crank the engine, a centrlfugal I switch responsiveto the speed of the generator, electro-responsive means for actuating the choker valve, a circuit for energizing said electro-responslve means, electromag- I netically operated means for controlling said energizing circuit a thermostat for controllin said energizing circuit, said electromag- I ing interdependent whereby the interruption netically operated means and thermostat beof the energizing circuit will depend on 0th.

In a power system in combination, an internal'combustion engine provided with a choker valve, a generator dis osed to be driven by the engine, a batterydisposed to be connected across the generator to operate it as a motor to crank the engine, a centrifugal switch responsive to the speed of the generator, electromagnetic means for actuating the choker valve, a circuit for energizing the electromagnetic means, means dependent upon the speed of generator for interrupting the circuit, means dependent upon temperature for interrupting the circuit, said circuit interrupting means, being dependent upon the I generator speed, and said temperature responsive means being interdependent on both temperature andspeed to prevent the interruption of the circuit before both the'speed I and temperature conditions are fulfilled.

4. In a system for controlling the chok- 7 ing operation of an internal combustion engine provided with a carburetor and a choker valve therefor, in combination, a coil for operating said valve, a switch for controlling said coil, means for closing said switch when a cranking operation for the engine is {performed, means responsive to the speed 0 the engine for deenergi z'ing said switch closing means at a predetermined engine speed, and

thermal responsive means for opemng said valve, in combination, a coil for operating said valve, a switch for establishing an energizing circuit for said valve operating coil, a coil forclosing said switch responsive to the cranking of the engine, said switch closing coil being disposed to oppose the opening of said switch if the engine speed is below a predetermined valve, means responsive to a predetermined speed of the engine for deenergizing said switch closing coil, and temperature responsive means rendered active upon the closing of said switch for opening said switch to interrupt the choking of said carburetor after a predetermined length of time, said choking of the carburetor being interrupted only when the engine-'speed-responsive device has operated.

6. In a system for controlling the choking operation of an internal combustion engine provided With a carburetor having a choker valve therefor, in combination, means for cranking said engine, means responsive to the cranking of said engine for actuating said choker valve, temperature responsive means for controlling said valveactuating means, and means responsive to thespeed of said engine for precluding theoperation of said temperature responsive means until the speed oflsaid engine has reached a predetermined va ue.

In testimony whereof, I have'hereunto subscribedmy name this first day of December, 1928.

; THOMAS. W. DRURY. 

